NYSL means 'Niru nari Yaku nari Suki ni shiro License' in Japanese.
It is originally written by k.inaba.
Translated into English,
it means like 'Do what you want'.
So,
basic stance is similar as WTFPL.
However,
threre are the following differences:

"No warranty" disclaimer is explicitly included.

Modified version of the software MUST be distributed under the responsibility of the distributer.